Brief History

Genbao castle (玄蕃尾城) is located at a ridge of Yanagaseyama mountain, one of 450 meter height above sea level located at the border of Omi province (Shiga prefecture) and Echizen province (Fukui prefecture). The border area of Omi province and Echizen province is an important area as an entrance into Hokuriku region from Kinki region, but is separated by steep mountains with many valleys. Historically roads connect both area are built along these valleys, and from Omi side there are two main roads of which one passes Yamagasetoge path toward west to Tsuruga area, and another goes directly northward toward Fukui plain via Kinometoge path. The place of Genbao castle is a separation point of these two roads, and even in modern era railway tunnel directly passed just below of the castle site in old day.

Five regional commanders of Oda clan

In 1582, central ruler Nobunaga Oda (1534-1582) who seized whole part of central Japan was quite close to the unification of Japan. Nobunaga placed five confident generals as regional commanders, and gave them large army and let them fight against enemies of each front. Hideyoshi Hashiba (1537-1598, later Hideyoshi Toyotomi), who rose up from son of poor pheasant by his talent, located at Sanyo area and gradually suppressed Mouri clan, the strongest enemy at Chugoku region. In Hokuriku region Katsuie Shibata (1522-1583), a veteran general activated as a vanguard of Oda army from the generation of Nobuhide Oda (1510-1551), the father of Nobunaga, fought with Uesugi clan which lost Kenshin Uesugi (1530-1578), the leader praised as a god of war, and lost their power during internal conflict after the death of Kenshin. Katsuie built Kitanosho castle (Fukui prefecture) as his main base, and steadily pushed up the front against Uesugi army toward northeast.At Kanto region newly seized by the fall of Takeda clan, Kazumasu Takigawa (1525-1586) who was said as a descendant of Ninja and well managed gunners was appointed as a magistrate of Nobunaga and communicated with remaining warlords such as Hojyo clan or Date clan. Nobutada Oda (1557-1582), the eldest son and successor, individually held Tokai region as a next leader of Oda clan, not as a general.Toward Shikoku island where Chosokabe clan grew their power, new regional army lead by Nobutaka Oda (1558-1583), the third son of Nobunaga and Nagahide Niwa (1535-1583), a general who served Nobunaga from youth, was established and prepared invasion toward Shikoku island. Additionally, Kinki region where was the main base of Nobunaga was managed by Mitushide Akechi (1528-1582), who was both good at administration and military affairs, and rose from wanderer to the highest position of Oda clan.

Coup d'etat and revenge

But in June 2 (old calendar), Mitsuhide Akechi suddenly made a coup d’etat against Nobunaga and assaulted him who stayed at Honnoji temple in Kyoto city with only small guards. This incident is called as “Honnoji no Hen” (incident of Honnoji), and the actual reason of this attempt is still unknown but there was a best situation to kill Nobunaga. Nobunaga killed himself at a burning Honnoji temple and his successor Nobunata Oda (1557-1582) did the same with major retainers, thus Oda clan lost its core and collapsed.Mitsuhide planned to seize Kinki region while other regional commanders faces their enemy and let his government as an accomplished fact, but Hideyoshi Hashiba made peace with Mouri clan hiding the death of Nobunaga, and quickly returned to Kinki region in 10 days after the incident and gathered small lords hesitating to support Mitsuhide.

Hideyoshi and Mitsuhide fought at the place of Yamazaki where is a narrow valley between Kyoto city and Osaka city, but Hideyoshi had a larger army and the pretext of revenge of his master finally defeated Mitsuhide. Mitsuhide tried to run away to his residence Sakamoto castle, but was killed by local people during his escape.

New regime after Kiyosu conference

After making a revenge of his master, commanders of Oda clan gathered at Kiyosu castle and had a conference to decided new order. As Takigawa army collapsed by Hojyo clan and still on running away, Hideyoshi, Katsuie, Nagahide and Tsuneoki Ikeda (1536-1584), brother in law of Nobunaga, discussed on the allocation of the territory. Based on the his achievement, Hideyoshi seized Kyoto and Osaka era where is economically and politically important and rose up to the virtual successor of Nobunaga.On the other hand, Katsuie Shibata, a veteran general and strongest commander of Oda army, could not contribute to the revenge of Nobunaga. Just at the time of the incident of Honnoji, Katsuie fell Uozu castle (Toyama prefecture) and forced 13 Uesugi generals to die, and could not make peace with Uesugi clan. And in Hokuriku region where was the territory of Shibata army there still survivors of Ikko Ikki group which was suppressed by Katsuie, and Katsuie who heard the news of Honnoji had to guard their territory and put down these rebel. After this Katsuie raised his army to beat Mitsuhide, but during his march Mitsuhide was already defeated by Hideyoshi. At this conference Katsuie just had Nagahama castle, where was former residence of Hideyoshi.

Start of Diadochi wars

After the death of Nobunata Oda, the eldest son of Nobunaga, there remained Nobukatsu Oda (1558-1630) and Nobutaka Oda (1558-1583), the second and third son of Nobunaga. Nobutaka was inferior to Nobukatsu but is seen as more talented, thus Nobutaka was appointed as a guardian of Hidenobu Oda (1580-1605), child of Nobutada who survived the incident and was nominated as a successor. Hideyoshi who took the initiative of Oda clan gradually tried to build his hegemony. Utilizing the hostility of Nobukatsu against Nobutaka, Hideyoshi connected to Nobukatsu and suppressed Nobutaka, and Nobutaka tried to confront in cooperation with Katsuie Shibata and Kazumasu Takigawa. Only after half year after the conference at Kiyosu castle, Diadochi war had began in winter of 1582.At first Hideyoshi surrounded Gifu castle where Nobutaka stayed and once let him surrender, and next captured Nagahama castle where was guarded by Katsutoyo Shibata (1556-1583), an adopted son of Katsuie. As heavy snow shut the road between Hokuriku region and Kinki region, Katsuie could not send reinforcement army to Nagahama castle. Next Hideyoshi who aimed one by one attack assaulted Ise province (Mie prefecture), the territory of Kazumasu Takigawa, but even though losing several castles Kazumasu barely stood the attack of Hideyoshi.In March 1583, Katsuie looked at this situation plowing the snow and marched from his main base Kitanosho castle at Echizen province toward Omi province, to rescue attacked Takigawa clan. Katsuie built Genbao Castle at the top of Yanagase mountain as his front headquarter, and generals of Shibata army such as Morimasa Sakuma (1554-1583) or Toshiie Maeda (1538-1599) stayed connecting ridges toward south. In response to this, Hideyoshi also placed his army over the hills surrounding Lake Yogo, and built a defense line toward north. Both army built forts at neighbor hills faced around Shizugatake mountain and Lake Yogoko over one month, thus the situation was totally fixed.

Reasonably built front line headquarter

As being built as a temporal front line base, Genbao castle did not have splendid elements such as stone walls or huge building. But therefore, this castle was built based on a clear and reasonable plan purified for its purpose. Each area of the castle is well shaped, and this shows this castle was built with time and effort.The purpose of front line base is a) to securely hold the commander and staffs and protect them from assassination or small size attack, b) watch the battlefield and command the army, and c) hold the supply such as food or ammunition to deliver to the front line. Genbao castle spreads along the ridge continues north and southward. The central area of the castle is a square shaped area of about 60 meter long, and has a basement of main building at its northeast corner. As southward of the castle is the expected attack side, there are two narrow buffer area before the central area which are guarded by folding gate to delay the enemy attack. Entrance to the central area is protected by a front fort of round shape, by which defense side can attack intruders from upward and start a counter attack.At the east of central area, where faces the valley and can see the front area toward Hashiba army, a small flat place to show the beacon to the friend army was built. It might be a magnificent view that Katsuie made a order by signal fire from Genbao castle at higher place, toward his army spread like a folding fan toward lower connecting ridges spread toward southward.On the other hand, at the north side of the central area which connected to his territory, there was a large flat area which is also about 60 mere square and used as a storage of supplies. Considering low possibility of enemy attack and convenience of supply transport, backside gate of the castle is a simple and wide gate without folding route, in contrast to the front side. Total length of the castle is about 150 meter and not so large one, and this castle was not intended to fight against large army.

Process of the battle of Shizugatake

In April, Nobutaka Oda once surrendered to Hideyoshi raised his army again at Gifu castle. It is unknown if this is intentional to break the dead rock or not, but Hideyoshi left this front with most of his army and siege Gifu castle. Seeing Hideyoshi’s absence as an opportunity, Morimasa Sakuma who was known his braveness as "Oni Genba" (demon Genba) detoured Lake Yogo and directly assaulted Kiyohide Nakagawa (1542-1583), a general of Hideyoshi side and guarded Oiwayama fort and killed him. Furthermore Morimasa attacked Ukon Takayama who stayed next place and, let him run and protruded into the north shore of Lake Yogo. This attack might be performed to divide Hashiba army and Nagahide Niwa who had a territory at the western shore of Lake Biwako, but Katsuie who feared to break the defense line ordered Morimasa to comeback. Strategically Katsuie had to rescue his ally Kazumasu Takigawa and Nobutaka Oda, but tactically Katsuie onld had half army of Hideyoshi and had to secure the front to give a pressure to Hideyoshi. But Morimasa declined to retreat from his position, and in the meantime Hideyoshi quickly returned from Gifu castle to the front with his large army. Morimasa well stood against the attack of Hideyoshi, but suddenly Toshiie Maeda who was the friend of Hideyoshi left the battlefield, and losing its moral Shibata army finally collapsed. As above Genbao castle was not intended to fight against large army, Katsuie did not besiege at Genbao castle and directly run away toward his residence Kitanosho castle then suicided at there. Hideyoshi who won against Katsuie next forced Nobutaka to die and Kazumasu Takigawa to surrender, and fixed his position as next ruler. This battle is called as the battle of Shizugatake, using the name of the site.

Afterward of the castle

Now no building remains at castle site but clay walls and dry moats well remains over the ridge. Seeing the reasonably built Genbao castle, even though being defeated, Katsuie also deserved as a main character of Diadochi wars after Nobunaga. Even though being a sober and not so famous castle located over steep mountain at deep inland, it is interesting castle as a good example of planning and worth for visiting if possible.